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火灾作用下海洋平台结构响应分析 总被引：1，自引：0，他引：1
结合BZ28-1南井口平台导管架,建立了海洋平台结构有限元计算模型。采用弹塑性分析方法,并应用温度升高时钢材的非线性应力/应变关系,采用火灾的标准温度-时间曲线建立平台结构温度随时间的变化模型,基于能量守恒原理建立热传导微分方程,计算热传导和对流对结构温度的影响,分析得到受火区域构件的温度场。依据钢材性能随温度升高的变化,分析火灾荷载下平台结构的响应。火灾发生时,平台结构中的构件在火温的作用下,温度逐渐升高,虽然作用在结构上的荷载不变,但由于钢材的弹性模量和屈服强度都急剧下降,使平台结构的承载能力下降;当温度上升到600℃以上时,平台结构就形成足够数目的塑性铰,使结构达到极限破坏状态。通过计算分析表明,当火灾作用6 min后,着火房间构件发生严重屈曲,但平台结构整体性能保持良好;当火灾作用22 min后,受火区域构件都发生了较大的变形,引起平台结构的毁损和倾覆。 相似文献
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深海钢悬链立管触地点动力响应分析 总被引：1，自引：0，他引：1
研究深海钢悬链立管(SCR)在海洋环境载荷作用下的动力响应.利用非线性弹簧模拟立管与海床触地点的耦合模型,通过模态分析得到钢悬链立管的动力特性参数;时域动力响应分析获得不同工况下触地点及典型部位的位移、弯矩和应力时程.比较分析表明:浮体垂荡运动对触地点的应力状态影响较大,触地点附近存在钢悬链立管动力响应过程中的位移极值点和弯矩极值点.所提方法为触地点区域模拟分析提供了新思路,给出的分析结论对钢悬链立管设计有一定借鉴意义. 相似文献
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在时域内分析深水钢悬链立管在平台运动和波流载荷共同作用下的非线性动力响应;采用雨流计数法处理立管节点应力的时间历程,选用DoE.E型S-N曲线分析立管在单一海况和平台运动联合作用下的疲劳损伤;将各方向含概率分布的疲劳损伤进行叠加,得到立管整体的全方向疲劳损伤及疲劳寿命。平台的运动为六自由度的运动预报数据,波流载荷由某海域实际的波浪统计数据采用Morison公式计算所得。计算结果表明钢悬链立管疲劳寿命的极值点分别位于悬挂点附近和触地点附近,对立管疲劳寿命极值点各方向疲劳损伤分布情况进行了分析。所提方法为钢悬链立管疲劳分析提供了新思路,给出的结论对钢悬链立管设计分析有一定借鉴意义。 相似文献
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在海况条件下,钢筋混凝土(R.C.)和预应力混凝土(P.C.)的耐久性和经济性比钢优越;轻质混凝土和钢纤维混凝土抗冲击和抗疲劳等性能也比较好,因此,自七十年代初期起,在海洋工程中的应用日益广泛,发展迅速。 (一)石油平台 1973年在挪威建造的Ekofish储油罐是世界上第一个大型混凝土重力式海工结构,标志着混凝土海工结构迅速发展的一个起点。迄今为止,在北海油田已建造安装了15个重力 相似文献
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考虑钢悬链线立管大变形的特性以及内流的影响,利用Kane方法和拉格朗日应变理论建立钢悬链线立管的二维动力学模型。将顶部浮体的激励简化为一个沿顺流向的周期作用力施加于立管顶部,采用平均加速度法求解立管的动力响应。探讨顶部浮体不同激励频率下立管的非线性动力响应以及内流流速的大小对管道共振响应幅值的影响。 相似文献
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Beam-noise spectrum levels were measured with high-resolution horizontal arrays of 22 to 100 wavelengths long at frequencies between 50 and 320 Hz in the Mediterranean Sea. Results indicate that the low-frequency noise field has two major components one of which is due to the dynamic and temporally variable distant shipping. Beam noise level differences of 10 to 20 dB were observed between the resolved distant shipping and the uncorrelated background noise. The measured distributions of beam-noise-intensity fluctuations were found to be non-Gaussian. The beam-noise-intensity distribution was found to depend on aperture length, frequency, bandwidth, integration time, and steering angle. The shapes of the beam-noise-intensity cumulative distribution functions were variable and qualitatively described by nonhomogeneous compound Poisson process as shown with a simulation of the shipping-induced noise field. Temporal characteristics of beam-noise-intensity fluctuations were found to have noise level fades at 30% probability below the median noise level with durations of 1 h for observations over 10 h. 相似文献
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Ship noise received on a horizontal array towed behind the ship is shown to be useful as a potentially diagnostic tool for estimating local acoustic bottom properties. In numerical simulations, tow-ship noise which bounces off the bottom is processed on a beamformer that shows the arrival angles; the beamformer output is readily interpreted by relating it to the Green's function of the acoustic wave equation. Simple signal processing is shown to be sufficient to extract the propagation angles of the "trapped" (i.e., propagating) modes of the acoustic waveguide. By relating the trapped modes to a basic geophysical model of the bottom, one can predict acoustic-propagation conditions for a particular bottom-interacting ocean acoustic environment. 相似文献
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滨州黄河公路大桥南引桥上部构造为单箱单室大悬臂连续现浇箱梁,跨径42m,2001年12月开工,经过17个月的艰苦施工,提前顺利竣工。对该项工程的施工经验做了总结。 相似文献
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Calderone S. Intilisano G. Mantica P. Montrosset I. Orta R. 《Oceanic Engineering, IEEE Journal of》1985,10(3):199-205
In this paper the Quasi-Particle (QP) technique has been applied for the first time to the study of beam propagation in slowly varying sound-speed profiles with an upper boundary, typical of some underwater acoustic environments. With the aim of testing the possibilities and the limitations of this new technique, particular attention has been devoted to special effects. The results of this analysis have been used to give some criteria for a proper modeling of the ocean environment from the Quasi-Particle point of view. 相似文献
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An adaptive noise cancelling (ANC) technique involving a joint-process deterministic least-squares lattice filter was applied to the Sea Beam bathymetric survey system data. The filtering scheme used in Sea Beam adversely affects the underlying acoustic return and may also lead to bathymetric artifacts. The authors investigate a possible remedy for this sidelobe interference problem offered by ANC coupled with signal preservation, provided both amplitude and phase information. The joint-process deterministic least-squares lattice is the adaptive filter of choice because of its superior transit response in the presence of power discontinuities. A REVGEN (reverberation generator) simulation (R.P. Goddard, 1985) of the Sea Beam system provided support for the proposed filtering technique. A complex data acquisition system was designed and built to record the in-phase and quadrature component of Sea Beam returns. Initial ANC processing of these recorded Sea Beam data provided satisfactory sidelobe interference cancellation with no noticeable degradation of the actual bottom returns 相似文献
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辛几何算法是专门针对动力学过程设计的算法,以提高动力学问题求解的精度与效率。高斯束偏移过程中的运动学与动力学射线追踪,从物理上讲是一个动力学过程,可以利用辛几何算法对其进行优化。本文将基于辛几何算法的运动学射线追踪引入高斯束叠前深度偏移中,并在推导了动力学射线追踪方程组的辛差分格式基础上,实现了基于辛几何算法的高斯束叠前深度偏移。模型实验表明,基于辛几何算法的运动学射线追踪,其效率与精度相比常规算法都具有一定优势,而基于辛几何算法的高斯束叠前深度偏移方法能够对复杂构造模型精确成像。 相似文献
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